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The Single UNIX &reg; Specification, Version 2<br>
Copyright &copy; 1997 The Open Group

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<h4><a name = "tag_000_002_014">&nbsp;</a>NAME</h4><blockquote>
cos - cosine function
</blockquote><h4><a name = "tag_000_002_015">&nbsp;</a>SYNOPSIS</h4><blockquote>
<pre><code>

#include &lt;<a href="math.h.html">math.h</a>&gt;

double cos(double <i>x</i>);
</code>
</pre>
</blockquote><h4><a name = "tag_000_002_016">&nbsp;</a>DESCRIPTION</h4><blockquote>
The
<i>cos()</i>
function computes the cosine of
<i>x</i>,
measured in radians.
<p>
An application wishing to check for error situations should set
<i>errno</i>
to 0 before calling
<i>cos()</i>.
If
<i>errno</i>
is non-zero on return,
or the returned value is NaN,
an error has occurred.
</blockquote><h4><a name = "tag_000_002_017">&nbsp;</a>RETURN VALUE</h4><blockquote>
Upon successful completion,
<i>cos()</i>
returns the cosine of
<i>x</i>.
<p>
If
<i>x</i>
is NaN, NaN is returned and
<i>errno</i>
may be set to [EDOM].
<p>
If
<i>x</i>
is &plusmn;Inf, either 0 is returned and
<i>errno</i>
is set to [EDOM], or NaN is returned and
<i>errno</i>
may be set to [EDOM].
<p>
If the result underflows, 0 is returned and
<i>errno</i>
may be set to [ERANGE].
</blockquote><h4><a name = "tag_000_002_018">&nbsp;</a>ERRORS</h4><blockquote>
The
<i>cos()</i>
function may fail if:
<br>
<dl compact>

<dt>[EDOM]<dd>
The value of
<i>x</i>
is NaN or
<i>x</i>
is &plusmn;Inf.

<dt>[ERANGE]<dd>
The result underflows.

</dl>
<p>
No other errors will occur.
</blockquote><h4><a name = "tag_000_002_019">&nbsp;</a>EXAMPLES</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_002_020">&nbsp;</a>APPLICATION USAGE</h4><blockquote>
The
<i>cos()</i>
function may lose accuracy when its argument is far from 0.
</blockquote><h4><a name = "tag_000_002_021">&nbsp;</a>FUTURE DIRECTIONS</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_002_022">&nbsp;</a>SEE ALSO</h4><blockquote>
<i><a href="acos.html">acos()</a></i>,
<i><a href="isnan.html">isnan()</a></i>,
<i><a href="sin.html">sin()</a></i>,
<i><a href="tan.html">tan()</a></i>,
<i><a href="math.h.html">&lt;math.h&gt;</a></i>.
</blockquote><h4>DERIVATION</h4><blockquote>
Derived from Issue 1 of the SVID.
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UNIX &reg; is a registered Trademark of The Open Group.<br>
Copyright &copy; 1997 The Open Group
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